1. Field of the Present Invention
The present invention relates to a positioning method and system, and more particularly to a self-contained/interruption-free positioning method and system for the earth's surface applications. The system of the present invention possesses the operational flexibility of capability of hand-held and the earth's surface vehicle applications, including air, land, and water vehicles, to determine position information of a user on the earth surface with high accuracy.
2. Description of Related Arts
Currently, most of the earth surface navigators depend on the GPS (Global Positioning System). The GPS is a dual-use, satellite-based radio-navigation system, which is owned, deployed, and operated by the U.S. Department of Defense, but is available for commercial uses around the world to provide accurate location and timing data. Unfortunately, GPS is vulnerable to jamming and shadowing, especially in the earth's surface applications, so that a GPS receiver often cannot provide continuous positioning information without interruption, especially in urban areas. For commercial and scientific the earth's surface applications, it is very important to obtain continuous positioning information in urban areas.
Traditionally, an inertial navigation system (INS) does not need to receive any external radio frequency signals to output position data continuously. However, the cost, size, power, and position-drift characteristics of conventional inertial navigation systems prohibit them from use in commercial the earth's surface navigation applications.
Therefore, it is very desirable to develop a positioning system with reasonable size and weight and power consumption for the earth surface operation without interruption, which can be used in the areas where GPS signals are not available, such as inside buildings, tunnels, forested areas, urbanized terrain, and heavy jamming environments.